The Different Forms of Flowers on Plants of the Same SpeciesDarwin, Charles
Science
The Different Forms of Flowers on Plants of the Same Species
Darwin, Charles
Fertilization of plants; Heterostylism; Plant physiology; Plants -- Variation; Pollination
This long-styled plant produced a large crop of capsules, and in this respect
was one of the most fertile of the whole lot of nineteen plants. But the average
from ten capsules was only 35.9 seeds, with a maximum of 60 and a minimum of 8.
PLANT 12.
This long-styled plant produced very few capsules; and ten yielded an average of
only 15.4 seeds, with a maximum of 30 and a minimum of 4.
PLANT 13.
This plant offers an anomalous case; it flowered profusely, yet produced very
few capsules; but these contained numerous seeds. Ten capsules yielded an
average of 71.9 seeds, with a maximum of 95 and a minimum of 29. Considering
that this plant was illegitimate and illegitimately fertilised by its brother
long-styled seedlings, the average and the maximum are so remarkably high that I
cannot at all understand the case. We should remember that the average for a
legitimate plant legitimately fertilised is 93 seeds.]
CLASS 3. ILLEGITIMATE PLANTS RAISED FROM A SHORT-STYLED PARENT FERTILISED WITH
POLLEN FROM OWN-FORM MID-LENGTH STAMENS.
I raised from this union nine plants, of which eight were short-styled and one
long-styled; so that there seems to be a strong tendency in this form to
reproduce, when self-fertilised, the parent-form; but the tendency is not so
strong as with the long-styled. These nine plants never attained the full height
of legitimate plants growing close to them. The anthers were contabescent in
many of the flowers on several plants.
[PLANT 14.
This short-styled plant was allowed during 1865 to be freely and legitimately
fertilised by illegitimate plants descended from self-fertilised mid-, long- and
short-styled plants. Fifteen capsules yielded an average of 28.3 seeds, with a
maximum of 51 and a minimum of 11; hence this plant produced only 33 per cent of
the proper number of seeds. The seeds themselves were small and irregular in
shape. Although so sterile on the female side, none of the anthers were
contabescent.
PLANT 15.
This short-styled plant, treated like the last during the same year, yielded an
average, from fifteen capsules, of 27 seeds, with a maximum of 49 and a minimum
of 7. But two poor capsules may be rejected, and then the average rises to 32.6,
with the same maximum of 49 and a minimum of 20; so that this plant attained 38
per cent of the normal standard of fertility, and was rather more fertile than
the last, yet many of the anthers were contabescent.
PLANT 16.
This short-styled plant, treated like the two last, yielded from ten capsules an
average of 77.8 seeds, with a maximum of 97 and a minimum of 60; so that this
plant produced 94 per cent of the full number of seeds.
PLANT 17.
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